1. Field of the Invention
The present invention relates to an azeotropic mixture of hydrogen fluoride (hereinafter referred to as "HF") and 1,1,1-trifluoro-2-chloroethane (hereinafter referred to as "R-133a ") and a process for the purification of R-133a by removing HF from a mixture comprising HF and R-133a. R-133a is of interest since it is one representative cooling medium which can replace dichlorodifluoromethane. Also R-133a is a suitable raw material of HFC-134a (1,1,1,2-tetrafluoroethane) and it is a suitable raw material of trifluoroethanol.
2. Description of the Related Art
R-133a is generally produced by reacting a carbon chloride such as trichloroethylene with HF. HF is removed from a reaction mixture comprising HF and R-133a as main components by washing the mixture with an aqueous solution. This technique is undesirable since a large amount of alkali is required to neutralize the washing solution.